Management process for an open anode furnace

ABSTRACT

A device and method for measuring the operating condition of an open anode furnace, includes at least one sensor for measuring the temperature and/or determining the fuel quantity or the burner capacity of the burners allocated to the anode furnace, or for determining the opacity of the air, and for the independent and automatic control of the process management of the anode furnace. This is achieved by at least one measuring device for measuring the throughput of air flowing through the anode furnace provided in an air duct of the anode furnace through which air flows. The measured values are evaluated by an electronic control unit, and the electronic control unit sets the operating condition of the anode furnace according to the particular measured values.

The present invention relates to a management process for an open anodefurnace in accordance with the pre-characterizing part of Clause 1 aswell as to a device for measuring the operating status of an open anodefurnace and for managing its process in accordance with thepre-characterizing part of Clause 5.

To date, an open or covered anode furnace has been operated in such away that the specialist personnel operating the anode furnace have torely on many years of professional experience to enable the workers tocontrol the anode furnace. This means that the specialist personnelresponsible for operation regulate the burner power, for example, inorder to increase or reduce the temperature in the burner zones. Thetemperature is measured at various points in the anode furnace for thispurpose.

However, an anode furnace control method of this type has thedisadvantage that the specialist personnel are often unable to achievethe optimum operating setting of the anode furnace because informationis lacking. This is because the parameters that are decisive in terms ofoptimum energy utilization can only be inadequately assessed andestimated by the specialists. For example, it is conceivable that anobstacle could occur within the air duct that could under certaincircumstances cause a local reduction in the volume of air passingthrough this area of the anode furnace, leading to a rise in temperaturewhereas there may be a drop in temperature at another point. Evenincreasing the burner power has no effect in the event of a reduction inthe throughput of air in the area of the burner, because the loweramount of heating air available does not transport the additionallyinput burner energy to the anodes immediately with the effect that theburner energy is applied to the walls of the anode furnace. This,however, leads to significant damage to the anode furnace because thewalls of the anode furnace are not designed to withstand such anelevated level of heat stress.

Furthermore, it is disadvantageous that the personnel operating theanode furnace cannot reliably estimate at what moment a section of theanode furnace has become unusable and therefore must be renewed.Instead, such decisions have in the past been based on statisticalobservations and values drawn from experience, which in some cases hasled to a section being renewed too soon or even too late. This causesunnecessary operating costs because the energy consumption increases.

Furthermore, it is highly costly to operate a faulty section or asection which is not being used optimally in terms of energy because theanode furnace requires additional energy in order to burn the anodes itcontains.

To date, no device for automatic control of an anode furnace has beendisclosed.

It is therefore the task of the present invention to provide amanagement process for an anode furnace of the aforementioned type, bymeans of which the anode furnace can be operated automatically over arelatively long period. This process is intended to provide measuringparameters by means of which an electronic control unit automaticallyundertakes the process management of the anode furnace. Also, theservice life of the anode furnace should be extended because the processmanagement remains within an optimum energy band. Furthermore, it is thetask of the present invention to provide a device by means of which theprocess management of the anode furnace can be undertaken.

The task in accordance with the present invention for managing theprocess of the anode furnace is accomplished by the features of thecharacterizing parts of patent claims 1 and 5, and the task forautomatic process management of the anode furnace is accomplished by thedevice in accordance with the characterizing part of patent claim 6.

Further advantageous embodiments of the invention are apparent from thesubordinate claims.

By means of the device and process in accordance with the presentinvention, it is possible to measure a heating duct index that ispermanently adjusted to the actual operating situation in the anodefurnace. In this case, an electronic control unit allocated to thedevice evaluates the measurement results and compares these with apredefined or mathematically calculated actual operating condition, andadapts the actual operating status to the optimum actual value of theanode furnace. This provides an advantageous way of obviating the needfor specialist personnel in order to monitor and conduct the processmanagement of the anode furnace. Rather, the process management of theanode furnace can be based on precisely predefined values so as to makeit possible to operate the anode furnace with optimum use of energy.

Also, the relevant parameters are determined in each section of theanode furnace so that it is possible to verify clearly in which sectionwhich actions have to be taken.

For example, the electronic control unit increases or reduces the airthroughput through the anode furnace in accordance with the volume ofair actually needed in the individual zones. If necessary, it is alsopossible to increase or reduce the quantity of fuel in order to controlthe output of the burners so as to achieve the optimum energetictemperature required for combustion of the anodes.

Consequently, the process management of the anode furnace takes placefully automatically and requires only minor manual checks, for exampleto see whether the measuring instruments used are in need of repair andthat they are delivering correct measurement values. As a result, afully automatic furnace process management of this kind only requires asmall number of personnel which allows considerable personnel costsavings. In addition, process management is adapted to achieve anoptimum energy profile and therefore the energy consumption can bereduced to the magnitude required for optimum operation of the anodefurnace.

The drawing shows a sample embodiment configured in accordance with thepresent invention, the details of which are explained below. In thedrawing,

FIG. 1 shows an anode furnace consisting of three fires divided intothree zones, within which a plurality of anodes are placed, with aschematic process management diagram for managing the process of theanode furnace, as a plan view,

FIG. 2 shows the anode furnace in accordance with FIG. 1, as a sideview, together with a temperature/time curve configured for the processmanagement of the anode furnace,

FIG. 3 shows two adjacent sections of the anode furnace in accordancewith FIG. 1, as a magnified plan view, and

FIG. 4 shows a cut-out of the anode furnace in accordance with FIG. 1and its sections, to which certain actual operation conditions areallocated.

FIGS. 1 to 4 show an anode furnace 2 to which a device 1 for processmanagement is allocated. The device 1 is intended to allow the anodefurnace 2 to be controlled automatically without the need for extensivemonitoring activity by the operating personnel.

The anode furnace 2 shown in FIG. 1 consists of three individual fireswith an identical structure. The structure and the mode of function ofthe anode furnace 2 is explained in more detail using the first fire.Each fire can be divided into three zones 3, 4 and 5 within whichdifferent operating conditions obtain. A plurality of anodes 7 that areto be burned are placed in one section 6 each in zone 3. In zone 4, thepositioned anodes 7 should be burned by three burners 10 and the burnedanodes should cool 7 in zone 5.

This means it is necessary for air to be channeled through the anodefurnace 2 and through the three zones 3, 4 and 5. An air duct 9 isprovided in the anode furnace 2 for this purpose and it connects theindividual sections 6 and therefore also the zones 3, 4 and 5 with oneanother. Furthermore, one damper flap 13 each is provided at the outputand input of the air duct 9 in order to allow the quantity of air suckedinto the air duct 9 to be controlled. A ventilator 14 is allocated tozone 3 and to the air duct 9 emerging there, by means of which the airis drawn through zones 3, 4 and 5 so that negative pressure exists inthe anode furnace 2. Consequently, air enters zone 5 of the anodefurnace 2 with the normal room temperature of the surrounding area andcools down the heated anodes 7. Nevertheless, there is a heat exchangebetween the anodes 7 and the sucked-in air, with the result that the airflowing into zone 4 is heated up. The three burners 10 further heat theair in zone 4, so that the anodes 7 placed there are exposed to theoperating temperature required for combustion.

The air flowing onwards into zone 3 therefore has a further elevatedtemperature, resulting in the anodes 7 placed in zone 3 being preheated.

Once the anodes in zone 4 have been burned up, the burners 10 are movedand transferred to zone 3 in order to burn the anodes 7 placed there. Inthis way, the anode furnace in its entirety represents a closed controlloop in which the following procedures occur in a recurring sequence:the three fires burn the positioned anodes 7, the anodes 7 cool down andthe anodes 7 are preheated; in a further three zones, meanwhile, theanodes 7 can be placed for burning or the burned anodes 7 can be removedfrom the anode furnace 2.

In order for the furnace management process to be performedautomatically, an electronic control unit 12 is allocated to eachindividual fire in the anode furnace 2. Furthermore, each of thesections 6 that form zones 3, 4 and 5 contains temperature sensors 16,sensors 17 for measuring the air throughput and sensors 20 for measuringthe opacity of the air, by which is meant the obtaining soot particleconcentration in the air. Temperature sensors 16 and sensors 17 and 20record measurement values for each of the sections 6 and pass these onto the electronic control unit 12.

The values measured in this way are used by the electronic control unit12 for creating a heating duct index that is made up of the measuredtemperature and/or the measured volumetric flow of air and/or thequantity of fuel supplied and the combustion capacity of the burners 10and/or the opacity of the fire generated by the burners 10 and/or thelevel of negative pressure obtaining in the zone 3, 4, 5 and/or theresulting temperature gradient of the fire generated by the burners 10.This heating duct index is now compared with an actual operating valueof the anode furnace 2 that has an optimum energy level. The electroniccontrol unit 12 makes appropriate adjustments in case there arediscrepancies. Following this, the heating duct index is once morecompared with the actual operating value.

The heating duct index is adjusted to the actual operating value by thedamper flap 13 at the entrance to the air duct 9 being opened or closedfurther, for example, with the effect that either more or less airenters the anode furnace 2. If necessary, the burner power of theburners 10 can also be adjusted by reducing or increasing the quantityof fuel. Controlling the ventilator 14 is also another way of increasingor reducing the air throughput. There are also individual dampers 13 inthe inside of the anode furnace 2 inside the air duct 9, which meansthat, in principle, each section 6 can be individually supplied withair.

FIG. 4 in particular shows that the individual sections 6 are monitoredwith the effect that it is possible to measure precisely which of thesections 6 are running with optimum energy utilization, or which of thesections 6 may be damaged as a result of the permanent stress caused byfluctuations in temperature and will have to be renewed. These sections6 are shown as a black field in FIG. 4, which means the operatingpersonnel can easily find out which of the sections 6 will have to becompletely renewed in the next cooling-down phase in order to achieve anoptimum use of energy during operation.

1. A management process for an open anode furnace (2) comprising aplurality of zones (3, 4, 5) connected together by an air duct (9),these zones (3, 4, 5) being composed of several sections (6) in whichanodes (7) to be combusted are placed and within which, to at least apartial extent, different operating conditions obtain, in which one ormore of the zones (3, 4, 5) have one or more burners (10) therein bymeans of which the corresponding zone (3, 4, 5) and air flowing throughthe zone is heated, and in which the air can be supplied through the airduct (9) into the individual zones (3, 4, 5) by means of negativepressure, characterized by the following steps: creating a heating ductindex for each of the one or more zones (3, 4, 5) the index being madeup of at least one of measured temperature, measured volumetric flow ofair, the quantity of fuel supplied, the combustion capacity of theburners (10), the opacity of a fire generated by the burners (10), thelevel of negative pressure obtaining in the zone (3, 4, 5), and theresulting temperature gradient of the fire generated by the burners(10); and making a comparison between the heating duct index and anactual operating value for the anode furnace (2), and undertaking aselected one of (1) changing the throughput volume of air flow, andsetting at least one of the quantity of fuel supplied and the combustioncapacity of the burners (10), depending on a difference between theheating duct index and the actual operating value of the anode furnace(2), and (2) exchanging at least one or more of the sections (6) formingthe zones (3, 4, 5) as soon as a tolerance limit between the heatingduct index and the actual operating value is exceeded.
 2. The process inaccordance with claim 1, characterized in that, mathematical methodscomprising one of linear multiple regression and statisticalcalculation, are used for creating the heating duct index.
 3. Theprocess in accordance with claim 1, characterized in that, themanagement of the anode furnace (2) is dynamically adapted by means ofthe heating duct index in accordance with the operating conditionmeasured in the sections (6).
 4. The process in accordance with claim 1,characterized in that, the volumetric flow of air is controlled by adamper flap (13) arranged in the air duct (9).
 5. A process foridentifying a condition of a heating duct in open and covered anodefurnaces, characterized in that, the condition of all heating ducts iscontinuously identified by means of a “heating duct index” that isformed by calculating together available measurement values usingmathematical methods comprising linear multiple regression, statisticalcalculation methods and fuzzy logic algorithms, the index beingcalculated from at least one of correlation of measurement data andposition of exhaust damper flaps on an exhaust ramp, the correlation ofmeasurement data and the measurement of opacity at a relevant fire in afurnace, the correlation of measurement data and the measurement ofnegative pressure at the relevant fire in the furnace, the correlationof measurement data and measurement of at least one of quantity of fuelsupplied and burner combustion capacity at the relevant fire in thefurnace, the correlation of measurement data and measurement oftemperatures in heating ducts of the relevant fire, the correlation ofmeasurement data and measurement of temperature gradient of the relevantfire in the heating ducts, the correlation of measurement data andmeasurement of the pressure ahead of the fire at the relevant fire inthe furnace system, the correlation of measurement data and themeasurement of at least one of cooling air volume and ventilatorcapacity of flap position at the relevant fire in the furnace system,and from an optical assessment using eyepieces disposed at the fire inthe furnace.
 6. A device for measuring operating conditions of an openanode furnace (2), the device comprising at least one sensor (16) for atleast one of measuring temperature and determining at least one of thequantity of fuel supplied and the combustion capacity of the burners(10) disposed in the anode furnace (2), and determining opacity of firegenerated by the burners, characterized in that, at least one measuringdevice (17) for measuring the throughput of air flowing through theanode furnace (2) is provided in an air duct (9) of the anode furnace(2) through which air flows, the measured values are evaluated by anelectronic control unit (12), and the electronic control unit (12) isadapted to set the operating condition of the anode furnace (2) inaccordance with the measured values.
 7. The device in accordance withclaim 6, characterized in that, at least one damper flap (13) isarranged in the air duct (9) of the anode furnace (2) and in that anopening angle of the damper flap (13) is adjusted by the electroniccontrol unit (12).
 8. The device in accordance with claim 7,characterized in that, each of the damper flaps (13) attached at aselected one of an input and output of the air duct (9).
 9. The devicein accordance with claim 6, characterized in that, at least oneventilator (14) is allocated to the air duct (9) of the anode furnace(2), and negative pressure generated by the ventilator (14) in the airduct (9) is adjusted by the electronic control unit (12).
 10. The devicein accordance with claim 6, characterized in that, the burner capacityof the individual burners (10) attached to the anode furnace (2) iscontrolled by the electronic control unit (12).